const fs = require('fs');

let promise = new Promise((resolve,reject)=>{
    fs.readFile('./1.txt','utf8',(err,result)=>{
        if(err != null){
            reject(err);
        }else{
            resolve(result);
        }
    });
});

promise.then((result)=>{
    console.log(result);
})
.catch((err)=>{
    console.log(err);
})